1. Field of the Invention
The present invention relates to a ratchet wrench, and more particularly to a ratchet wrench including two driving assemblies or devices for allowing the ratchet wrench to drive the fasteners with different driving torques.
2. Description of the Prior Art
Typical ratchet wrenches comprise a driving gear or cartridge rotatably received in an enlarged head of a handle, and a pivotal pawl attached to the driving gear or cartridge and engageable with an internal gear of the enlarged head of the handle for controlling the driving directions of the driving gear or cartridge by the enlarged head of the handle.
For example, U.S. Pat. No. 5,960,680 to Chen et al. discloses one of the typical ratchet wrenches comprising a reversing disc coupled to the pivotal pawl for actuating the pivotal pawl to selectively engage with the internal gear of the enlarged head of the handle in order to control the driving directions of the driving gear or cartridge by the enlarged head of the handle. However, the driving gear or cartridge may only be rotated or driven by the enlarged head of the handle for a single output torque but may not be rotated or driven by the enlarged head of the handle with different output torques.
U.S. Pat. No. 6,220,123 to Chen discloses another typical ratchet wrench comprising a rotating disc coupled to the pivotal pawl for actuating the pivotal pawl to selectively engage with the internal gear of the enlarged head of the handle in order to control the driving directions of the driving gear or cartridge by the enlarged head of the handle. However, similarly, the driving gear or cartridge may only be rotated or driven by the enlarged head of the handle for a single output torque but may not be rotated or driven by the head of the handle with different output torques.
U.S. Pat. No. 6,311,584 to Chu discloses a further typical ratchet wrench comprising a driving gear or cartridge rotatably received in an enlarged head of a handle, one or more rotating discs, reverse discs, or ratchet wheels rotatably received in the enlarged head of the handle and selectively coupled to the driving gear or cartridge for selectively rotating or driving the driving gear or cartridge with one output torque, and two pivotal pawls attached to the driving gear or cartridge and engageable with an internal gear of the enlarged head of the handle for controlling the driving directions of the driving gear or cartridge by the enlarged head of the handle and for selectively rotating or driving the driving gear or cartridge with a different output torque.
However, a knob is further required to be provided and includes an extension for engaging with two pawls and two actuating rods respectively in order to control the engagement between the driving gear or cartridge and the ratchet wheels or the engagement between the driving gear or cartridge and the internal gear of the enlarged head of the handle.
U.S. Pat. No. 6,457,386 to Chiang discloses a still further typical ratchet wrench comprising a drive member and two annular gears engaged in an enlarged head of a handle, and two pairs of pivotal pawls attached to the drive member and engageable with an internal gear of the enlarged head of the handle for controlling the driving directions of the drive member by the enlarged head of the handle and for selectively rotating or driving the drive member with different output torques.
However, a complicated control member and a rotating wheel are further required to be provided for engaging with the pawls in order to control the engagement between the drive member and the ratchet wheels or the engagement between the drive member and the internal gear of the enlarged head of the handle.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages of the conventional control mechanisms for the ratchet wrenches.